Abstract: The growth , development and yield of population of hybrid cotton YUZAO 35 was researched under different treatments with different level of fertilization in the same proportion of nitrogen ,phosphorus and potassium under sparse planting by 24000 plants per hectare. the results showed that increased the sowing rate of nitrogenous fertilizer, phosphate fertilizer and potash fertilizer promoted accumulation of population dry matter and increased leaf area obviously ,the bolls per plant and the total bolls of cotton population were increased also ,thus the biomass yield and economic yield were enhanced markedly . while the yield increasing become insignificant ,and the fertilizer effect as well as the percentage of pre-frost harvested lint reduced when the fertilizer sowing rate of nitrogen(N) ,phosphorus(P2O5) and potassium(K2O) per hectare exceeded 195kg/hm2,97.5kg/hm2and 136.5kg/hm2 respectively .